Not sure if it is what you want Matt but I've been looking into an 'Endless Pool' (pool with a current from www.endlesspools.co.uk) for me nd the missus. It's around 3.5 x 5.5 m long and doesn't need too much maintenance. It can also be assembled inside or out and taken apart when you move (remember that a pool doesn't add anything to your house price...rather takes it!). With the exchange rate at the moment it costs about £12k. We're personally hoping to put it in an extension but we'll see what mortgage rates are doing in the summer.

Off hopefully to try one at the w/e so can let you know if your interested.

Dave